Q&A

Q&A; First Aid or Not?

By C. CLAIBORNE RAY

Published: June 30, 1998

Q. Whatever happened to Mercurochrome and Merthiolate? How do they work?

A. Mercurochrome is a trade name for merbromin, a compound containing mercury and bromine. Merthiolate is a trade name for thimerosal, a compound containing mercury and sodium.

Both these compounds kill some (but not all) disease-causing microbes by denaturing enzymes and other proteins so that the microbes' metabolism is blocked; they do this by breaking up chemical bonds in the proteins.

Both have been widely used as topical antiseptics, applied to the surface of the skin of a living body. Thimerosal is still often used to help rid skin of bacteria before medical procedures. Mercurochrome is not widely used anymore.

Both Mercurochrome and Merthiolate (and iodine preparations, too) sting when applied to broken skin and can interfere with healing. Experts now recommend that first aid kits contain newer antibacterial creams, especially those containing bacitracins, a class of antibacterials first produced by other microorganisms.

A cut or scrape should first be washed with soap and water, and the first-aid cream should be put on with a sterile applicator, like a cotton swab, when the injury is clean and dry. C. CLAIBORNE RAY

Readers are invited to submit questions about science to Questions, Science Times, The New York Times, 229 West 43d Street, New York, N.Y. 10036. Questions of general interest will be answered in this column, but requests for medical advice cannot be honored and unpublished letters cannot be answered individually.